The present invention is related to heart valve replacement, and more particularly to devices, systems, and methods for transcatheter delivery of collapsible prosthetic heart valves.
Prosthetic heart valves that are collapsible to a relatively small circumferential size may be delivered into a patient less invasively than valves that are not collapsible. For example, a collapsible valve may be delivered into a patient via a tube-like delivery apparatus such as a catheter, a trocar, a laparoscopic instrument, or the like. This collapsibility may avoid the need for a more invasive procedure such as full open-chest, open-heart surgery.
Collapsible prosthetic heart valves typically take the form of a valve structure mounted on a stent. There are two types of stents on which the valve structures are ordinarily mounted: a self-expanding stent and a balloon-expandable stent. To place such a valve into a delivery apparatus and ultimately into a patient, the valve must first be collapsed or crimped to reduce its circumferential size. For example, a conventional collapsible prosthetic valve is typically collapsed and retained in a collapsed state by a sheath for delivery into the patient, for example, through a femoral artery.
When a collapsed prosthetic valve has reached the desired implant site in the patient (e.g., at or near the annulus of the patient's heart valve that is to be replaced by the prosthetic valve), the prosthetic valve may be deployed or released from the delivery apparatus and re-expanded to full operating size. For balloon-expandable valves, this generally involves releasing the entire valve, assuring its proper location, and then expanding a balloon positioned within the valve stent. For self-expanding valves, on the other hand, the stent automatically begins to expand as the sheath covering the valve is withdrawn.
Despite the various improvements that have been made to the collapsible prosthetic heart valve delivery process, conventional delivery devices, systems, and methods suffer from some shortcomings. For example, in conventional delivery devices for collapsible prosthetic valves such as the device 7 shown in FIG. 1, it may be difficult to control the alignment of the longitudinal axis of the distal sheath 8 relative to the geometric center of the native annulus 6 (i.e., planar alignment). During use of the device 7 to deliver a prosthetic valve to the native annulus 6, the distal tip 9 of the device may contact and stretch the inner wall 3 of the aortic arch 2, which may cause damage to the inner wall. Even if a steerable device 7 is used, it may be difficult to move the distal sheath 8 through the tight radius of the aortic arch 2 without contacting and stretching the inner wall 3. Also, during use of the device 7 for delivery of a prosthetic valve, calcified particles may be detached from the native valve or the inner wall 3 of the aorta 1, thereby forming emboli that may travel within the vascular system and cause a stroke or other vascular occlusion.
There therefore is a need for further improvements to the devices, systems, and methods for transcatheter delivery of collapsible prosthetic heart valves. Among other advantages, the present invention may address one or more of these needs.